A federal appeals court has temporarily blocked plans to build a new ballroom at the White House, ruling that major structural changes to the historic complex cannot move forward without approval from Congress.

In a 2–1 decision issued Friday, the U.S. Court of Appeals for the District of Columbia Circuit upheld a lower court order that paused construction of the proposed $400 million project. The case centers on plans by the Trump administration to replace the White House East Wing with a ballroom covering approximately 90,000 square feet.

The majority of the court found that such a significant alteration to a federally owned historic site falls under congressional authority rather than the sole discretion of the executive branch. Judges noted that the president serves as a temporary occupant of the White House and does not possess unilateral power to authorize large-scale modifications to the property.

The ruling keeps in place a preliminary injunction sought by the National Trust for Historic Preservation, which challenged the project after construction preparations began without congressional authorization.

Despite the setback, the appeals court delayed implementation of its order for 14 days, allowing the administration time to seek review from the U.S. Supreme Court.

President Donald Trump strongly criticized the decision on Truth Social, calling it politically motivated and announcing plans to appeal. He has repeatedly argued that the proposed ballroom would serve not only as an event venue but also as a security-enhanced facility capable of supporting emergency operations. According to Trump, the structure would incorporate protective features designed to address threats ranging from bomb attacks to drones and missile strikes.

The project’s estimated cost has risen considerably since it was first announced. Trump has attributed the increase to design expansions and upgraded construction standards intended to improve the building’s functionality and security.

Preservation advocates welcomed the court’s decision. Brent Leggs, president of the National Trust for Historic Preservation, said the ruling reinforces the public’s role in decisions affecting nationally significant historic landmarks.

The latest development follows earlier orders from U.S. District Judge Richard Leon, who halted above-ground construction activities while permitting certain underground work to continue. The Trump administration appealed those restrictions, leading to Friday’s ruling by the federal appeals court.

The legal battle now appears headed toward the Supreme Court, where the administration is expected to challenge the decision in the coming weeks.